Virus infection induces redistribution and membrane localization of the nuclear antigen La (SS-B): a possible mechanism for autoimmunity.

To investigate the possibility that anti-La (SS-B) antibodies in Sjögren's syndrome were induced by virus infection we studied the distribution of La in virus-infected human cell lines. Three monoclonal antibodies to La were used with monoclonal anti-Sm (derived from MRL/lpr lupus mice) and anti-rat immunoglobulin antibodies as controls. In uninfected cells La was predominantly in the nucleus. Twenty-four hours after infection of HEp-2 cells with adenovirus 2, the La and Sm antigens appeared to aggregate and accumulate in the periphery of the nucleus and, after 48 h, La was seen in the cytoplasm and cell membrane. No cytoplasmic or membrane expression of Sm was seen. Infection with adenovirus or cytomegalovirus caused a 2-13-fold increase in the concentration of La in three cell lines. Treatment of HE--2 cells with interferon-gamma (IFN-gamma) and infection with Epstein-Barr virus and cytomegalovirus caused cytoplasmic, but no definite membrane expression of La. The appearance of La on the surface of virally infected epithelial cells together with IFN-gamma induced class II expression could form the basis of a T cell dependent mechanism for anti-La autoantibody induction.